基于GIS的赣江流域环境生态数据库的建立

本文主要介绍了基于GIS的赣江流域环境生态数据库的建设目标，并就其主要方法、技术特点及主要功能进行了探讨。     

浅议环境与经济可持续发展

介绍了可持续发展的概念、特征，论述了环境与经济发展的关系以及我国可持续发展的战略选择。     

HPLC测定大气中的光气

报道了用０．２５％的苯胺溶液吸收大气中的光气，所形成的１，３－二苯基脲衍生物以高效液相色谱分析。方法回收率为９８．１％￣１００．８％，最低检出浓度为１．７×１０＾－４ｍｇ／ｍ＾３，线性范围为０．１￣３４０ｎｇ，相对标准偏差为１．２３％。     

Transport characteristics of gas phase ozone in unsaturated porous media for in-situ chemical oxidation

Encapsulation technology is being investigated as a method for controlling pH in situ at contaminated groundwater sites where pH may limit remediation of organic contaminants. This study examined the effectiveness of using KH2PO4 buffer encapsulated in a pH-sensitive coating to neutralize pH in laboratory sand columns (1.5-1) under a simulated groundwater flow rate and characterized the pattern of capsule release in the flow-through system. Denitrification was used in the columns to increase the pH of the pore water. Each of three columns was equipped with three miniature mesh wells to allow contact of the buffer with column pore water, but capsules (15 g) were inserted into only one column (amended). The two other columns served as amendment (no buffer) and abiotic (no denitrification) controls. Oxidation-reduction potential, dissolved organic and inorganic carbon, NH4+, NO3- +NO2-, PO(4)3-, and pH were measured in the influent, two side ports, and effluent of the columns over time. Near complete conversion of 80 mg N/1 of nitrate and 152 mg/l of ethanol per day resulted in a mean pH increase from 6.2 to 8.2 in the amendment control column. The amended column maintained the target pH of 7.0 +/- 0.2 for 4 weeks until the capsules began to be depleted, after which time the pH slowly started to increase. The capsules exhibited pulses of buffer release, and were effectively dissolved after 7.5 weeks of operation. Base-neutralizing capacity contributed by the encapsulated buffer over the entire study period, calculated as cation equivalents, was 120 mM compared to 8 mM without buffer. This study demonstrates the potential for this technology to mediate pH changes and provides the framework for future studies in the laboratory and in the field, in which pH is controlled in order to enhance organic contaminant remediation by pH-sensitive systems.     

Key factors in chemical reduction by hydrazine for recovery of precious metals

Most of the commonly used metal waste treatment approaches only allow removal of metals which are ultimately discarded as sludge and do not permit the reuse of the metals, resulting in a waste of raw materials. In this study, the recovery of precious metals of sliver and copper in a synthesized wastewater in batch reactors was investigated using a reduction method by hydrazine as the reducing agent. Recovery of metal ions was greatest at pH > 11. The presence of humic acid did not have negative effects on the recovery process. Varying dissolved oxygen levels in the hydrazine solution did not significantly affect the recovery of both metals while seeding and ageing processes resulted in an increase in the particle size of the solid obtained. Under competitive conditions between Cu2+ and Ag+ ions, the recovery of silver remained the same, while that of copper was enhanced.     

The toxicity and bioavailability of atrazine and molinate to Chironomus tepperi larvae in laboratory and river water in the presence and absence of sediment

Acute (10 day) semi-static toxicity tests in which the midge, Chironomus tepperi, were exposed to atrazine and molinate were conducted in laboratory water and in river water, in the absence and presence of sediment. The bioavailability measured as median lethal concentrations (LC50) and 95% fiducial limits (FLs) of atrazine to C. tepperi in laboratory water in the absence and presence of sediment were 16.6 (14.3-19.4) and 21.0 (18.2-24.1) mg l(-1), respectively while the corresponding values in river water were 16.7 (14.7-19.0) and 22.7 (20.3-25.4) mg l(-1), respectively. For molinate, the LC50 and FL values in laboratory water in the absence and presence of sediment were 8.8 (6.8-11.4) and 14.3 (12.4-16.4) mg l(-1), respectively and the corresponding values in river water were 9.3 (7.6-11.3) and 14.5 (12.4-16.9) mg l(-1), respectively. Atrazine has low toxicity (LC50 > 10 mg l(-1)) while molinate has moderate toxicity (1 mg l(-1) < LC50 < 10 mg l(-1)) to C. tepperi. River water did not significantly (P > 0.05) reduce the bioavailability of either chemical to C. tepperi. However, the presence of sediment did significantly (P < 0.05) reduce the bioavailability of both atrazine and molinate to C. tepperi.     

Agrobacterium-mediated transformation of Nicotiana attenuata, a model ecological expression system

Summary. Research into the genetic basis of the ecological sophistication of plants is hampered by the availability of transformable systems with a wealth of well-described ecological interactions. We present an Agrobacterium-mediated transformation system for the model ecological expression system, Nicotiana attenuata, a native tobacco that occupies the post-fire niche in the Great Basin Desert of North America. We describe a transformation vector and a transformation procedure that differs from the standard cultivated tobacco transformation protocols in its use of selectable markers, explants, media and cultivation conditions. We illustrate its utility in the transformations with genes coding for key enzymes in the oxylipin cascade (lipoxygenase, allene oxide synthase, hydroperoxide lyase) in antisense orientations and present high-throughput screens useful for the detection of altered phenotypes for the oxylipin cascade (green leaf volatiles and jasmonic acid after wounding). Received 14 March 2002; accepted 10 May 2002     

珠江三角洲典型地区蔬菜硝酸盐与亚硝酸盐污染评价

研究了珠江三角洲典型地区中山市大型蔬菜生产基地中9种蔬菜30个样品中硝酸盐与亚硝酸盐的污染现状,初步摸清了蔬菜中硝酸盐及亚硝酸盐的污染状况。并以WHO/FAO规定的日允许摄入量换算得到的标准评价了其主要蔬菜品种的硝酸盐污染状况。结果表明:在被调查的蔬菜中,硝酸盐含量由高到低依次为菜心→白菜>芥菜→空心菜→生菜→瓜果类,菜心、芥菜和白菜为严重污染,生菜与空心菜为重污染,瓜果类蔬菜为轻污染;亚硝酸盐含量普遍较低,均未超标。因而有必要采取有效的污染防治措施控制该地区蔬菜中的硝酸盐污染状况。     

河口潮滩沉积物对氨氮的等温吸附特性

以长江河口滨岸潮滩为研究对象 ,运用模拟实验的方法 ,研究了潮滩沉积物对氨氮的等温吸附特征 .结果表明 ,在模拟实验上覆水中氨氮的浓度 ( <1 40 μg·ml- 1 )范围内 ,沉积物对氨氮的吸附呈线性特征 .长江河口潮滩沉积物对氨氮的吸附系数在 3 81— 9 0 0之间 ,且与沉积物中有机碳 (TOC)的含量有良好的相关关系 (相关系数r =0 779,α =0 0 5 /) ,揭示了有机质控制着长江河口潮滩沉积物中氨氮的吸附行为 .模拟实验结果还发现 ,在淡水控制区域内 ,潮滩沉积物中固定态氨氮的含量处在 1 6 68— 33 73μg·g- 1 (dw)之间 ,而在海水所控制的潮滩沉积物中固定态氨氮的含量在 0 5 7— 6 36μg·g- 1 (dw)之间 ,这可能反映了研究区域内潮滩沉积物中固定态氨氮的含量主要受盐度控制     

饮用水源地浮游藻类群落特征及富营养化风险评价

为了解新立城水库藻类分布及富营养化特征,于枯水期和丰水期进行调查与分析,结果表明,新立城水库共鉴定出藻类29种,隶属于绿藻门、蓝藻门、硅藻门、隐藻门、金藻门、裸藻门和甲藻门共7门19科,其中绿藻门最多,通过生物多样性指数分析得到,枯水期水质优于丰水期;分析近10年水库水体理化性质得到水库总体上呈轻度富营养化状态,氮磷浓度较高,农业面源污染是导致水体中氮磷浓度偏高的主要原因。